The way you phrase things matters. And “common sense” is one of the bigger mis-namings of all time.
Sure, you’re probably thinking “because common sense isn’t common”. Ha ha.
But that’s the point – but not because of how many (or few) people “have it”.
It’s because “common sense” is not common – it’s highly specialized information, and frequently quite complex acculturation. Folks often use “common” here to mean either “universal” or “simple”, and neither is true.
Everybody knows you drive on the right side of the road. It’s common sense. Unless you’re somewhere where they don’t.
Seem too obvious? Okay how about this:
Everybody knows how big our “personal space” or “personal bubble” should be… except it was never consistent across cultures (It was a shock for me during my time in Korea). And now, layered on top of that, is how the pandemic has changed our idea of “normal” there.
When I’ve re-watched older episodes of, say, Taskmaster, it seems so strange that they’re all sitting so close together. And I suspect that people’s ideas of what “normal” personal space also maps to their views about the pandemic and masks.
The current confusion a lot of people have there as we’re in this phase of the pandemic really illustrates how “common sense” is something you learn. It’s a series of skills. You may never realize that you’re learning them, or deliberately set out to learn “common sense” (though some people do), but that’s what happens.
My mother, when I last visited, noted that I have never had a lot of “common sense”. Which, from her point of view, is, um, pretty accurate. It’s just mislabeled. I don’t always have “appropriate social interaction knowledge in contexts that are important to my mother.”
And then later in the day, she and my father asked me about using the proper pronouns and terms for LGBTQIA+ folks, because they’re good people, and wanted to be respectful and understand the social rules around that as well. That was (and is) “common sense” to me… and now it is for them too. 
So value your “common sense”, because it’s not simple. And show understanding of those without your idea of “common sense”, because you probably don’t share theirs.
 Ignorance is not a moral failing. Refusing to correct ignorance once you’re aware of it, however…